A Tunisian military court has sentenced a blogger to one year in prison on charges he insulted the army, his lawyers said, in a case rights activists fear may undermine freedoms won after the 2011 revolution.

The blogger, Yassin Ayari, was well-known in Tunisia for his criticism of former autocrat Zine El-Abidine Ben Ali and restrictions during his rule on freedom of expression. After the 2011 uprising that ousted Ben Ali, Ayari turned to political criticism of the army.

"A military court sentenced the blogger Yassin Ayari to a year on charges of insulting the army and impacting its morale after comments on Facebook criticized the performance of the defense minister," lawyer Malek Ben Amor said.

The army did not immediately return calls seeking comment on the case.

Ayari is the son of a military officer killed by Islamist militants in an attack in 2011. He was arrested at the airport last month upon arrival from Paris.

Tunisia has been praised for its democratic transition since the fall of Ben Ali, with free presidential and parliamentary elections last year and a new constitution that is seen by supporters as one of the most progressive in the region.

Last November, the secular party Nidaa Tounes, which includes officials of the former Ben Ali regime, won the most seats in parliament. Newly elected President Beji Caid Essebsi is also a former Ben Ali official.

Critics and some activists worry the return of old guard figures is a setback for the revolution, which aimed to sweep away the country's autocratic past.

Essebsi dismisses the criticism, saying he is president for all Tunisians. He says former Ben Ali officials like him are technocrats untainted by past corruption and abuses.

But the sentencing of a civilian by a military court has left some Tunisian activists and rights lawyers with questions, just as the new government is being named and starting work.

"Of course, there are worries about freedom of expression when someone is judged by a military court," said another blogger, Lina Ben Mhenni. "But I am not sure whether this has anything to do with Nidaa Tounes or the old regime types, as they haven't even named a government yet."